Podcast
Questions and Answers
Which of the following nucleotides has a ketone group?
Which of the following nucleotides has a ketone group?
Uracil is found in DNA.
Uracil is found in DNA.
False
What sugar is found in RNA?
What sugar is found in RNA?
ribose
Cytosine, Thymine, and Uracil are classified as ______ bases.
Cytosine, Thymine, and Uracil are classified as ______ bases.
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Match the following nucleobases with their characteristics:
Match the following nucleobases with their characteristics:
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Which type of bond connects nucleotides in a nucleic acid?
Which type of bond connects nucleotides in a nucleic acid?
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Adenosine triphosphate (ATP) contains deoxyribose as its sugar.
Adenosine triphosphate (ATP) contains deoxyribose as its sugar.
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What is a function of cyclic adenosine monophosphate (cAMP)?
What is a function of cyclic adenosine monophosphate (cAMP)?
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The splitting of two end phosphate groups in nucleotides supplies energy necessary for the formation of ______ bonds.
The splitting of two end phosphate groups in nucleotides supplies energy necessary for the formation of ______ bonds.
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Which amino acids are necessary for purine synthesis?
Which amino acids are necessary for purine synthesis?
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What components make up a nucleotide?
What components make up a nucleotide?
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Cytosine forms stronger bonds with guanine than adenine forms with thymine.
Cytosine forms stronger bonds with guanine than adenine forms with thymine.
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What type of bond links a nucleoside and a phosphate group in a nucleotide?
What type of bond links a nucleoside and a phosphate group in a nucleotide?
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Cytosine has ___ hydrogen bond donors and forms a strong bond with guanine.
Cytosine has ___ hydrogen bond donors and forms a strong bond with guanine.
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Match the following nucleobases with their descriptions:
Match the following nucleobases with their descriptions:
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Which amino acids are required for purine synthesis?
Which amino acids are required for purine synthesis?
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Deoxyribose sugar is found in nucleosides but not in nucleotides.
Deoxyribose sugar is found in nucleosides but not in nucleotides.
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What is the role of inosine during tRNA translation?
What is the role of inosine during tRNA translation?
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A ___ consists of a nitrogenous base and a sugar linked by an N-glycosidic bond.
A ___ consists of a nitrogenous base and a sugar linked by an N-glycosidic bond.
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The higher the number of cytosine-guanine bonds in DNA, the ___ its melting temperature.
The higher the number of cytosine-guanine bonds in DNA, the ___ its melting temperature.
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Study Notes
Nucleotide Structure
- Nucleotides are composed of three components: a nitrogenous base (purine or pyrimidine), a pentose sugar (ribose or deoxyribose), and a phosphate group.
- A nucleoside is formed by the base and sugar linked by an N-glycosidic bond.
- A nucleotide is formed by a nucleoside and a phosphate group linked by a 3'-5' phosphodiester bond.
Nucleobases
- Cytosine (C) forms 3 hydrogen bonds with guanine (G), making a stronger bond than the 2 hydrogen bonds formed by adenine (A) with thymine (T) or uracil (U).
- Higher C-G content in DNA correlates with increased melting temperature.
- Thymine (T) is found only in DNA and contains a methyl group. Uracil (U) is only found in RNA.
- Hypoxanthine, created from adenine via deamination, is present as inosine in tRNA, vital for wobble base pairing.
- Xanthine, an intermediate in purine metabolism, arises from guanine via deamination.
Purine and Pyrimidine Overview
| Rings | Base | Notable Characteristics | As a nucleoside unit in RNA | As a nucleoside unit in DNA |
|---|---|---|---|---|
| 1 | Cytosine (C) | Forms 3 hydrogen bonds, major contributor to DNA stability | Cytidine | Deoxycytidine |
| Thymine (T) | Contains methyl group, only in DNA | Not present | Thymidine | |
| Uracil (U) | Only in RNA | Uridine | Not present | |
| 2 | Adenine (A) | Forms 2 hydrogen bonds | Adenosine | Deoxyadenosine |
| Guanine (G) | Contains a ketone group, forms 3 hydrogen bonds | Guanosine | Deoxyguanosine |
Amino Acids for Purine Synthesis
- Purine synthesis requires glycine, aspartate, and glutamine.
Nucleic Acid Sugars
- The sugar in nucleic acids is a pentose, a five-atom ring.
- RNA contains ribose.
- DNA contains deoxyribose.
- Bases are attached to sugars via N-glycosidic bonds.
- Phosphate groups are attached to sugars via phosphodiester bonds.
Phosphate Groups
- Nucleotides can have one, two, or three phosphate groups.
- The splitting of the two terminal phosphates on a nucleotide adding to a growing chain provides energy for the phosphodiester bonds in the DNA backbone.
Nucleotide Functions and Derivatives
- Nucleotides are crucial building blocks of nucleic acids.
- They act as energy carriers, with ATP being a universal cellular energy source. Other energy carrying molecules like GTP are also critical.
- They are signaling molecules, like cAMP and cGMP, often acting as second messengers.
- They act as activators for transferring molecules (e.g., UDP-glucose in glycogenesis).
- They are also regulatory molecules affecting enzyme responses in signal transduction pathways (e.g., GTP binding to G-proteins).
- They are carrier molecules (e.g., NAD+/NADH and FAD/FADH2).
- Other derivatives include: S-adenosylmethionine (SAM), key in methylation reactions; and 3'-phosphoadenosine-5'-phosphosulfate (PAPS), as a sulfate donor.
- Note, ATP contains ribose, not deoxyribose, containing a 2' hydroxyl group.
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Description
Explore the fundamental components of nucleotides, including their structure and the differences between purines and pyrimidines. This quiz dives into the bonding properties of nucleobases and the role of ribose and deoxyribose in nucleotides. Test your knowledge of nucleotide chemistry and molecular biology concepts.
